This invention concerns energy conversion fibers and other objects, containing a component, such as a piezoelectric material, that can convert and consume external mechanical energy of vibration and sound pressure into another form of energy, such as electrical energy, sound reducing materials that use such fibers or other objects, and a sound reducing structure that can be used in vehicles, housing, building and other facilities.
As a material in a sound insulating structure for motor vehicle or buildings, a document D1(Published Japanese Patent Application Kokai Publication No. H07(1995)-223478) proposes a laminate of a sound absorbing material layered between plate materials such as metal and resin materials. As a developed form of such a sound insulating material, a document D2 (Published Japanese Patent Application Kokai Publication No. H08(1996)-246573 discloses a ferroelectric polymer film.
The sound-absorbing material disclosed in document D2 (H08(1996)-246573) was developed in view of the increase in the weight and/or the occupied volume in the above-mentioned sound insulating laminate structure of plate materials and sound absorbing material. However, when a ferroelectric material is used as a film, the capacitance (C) is proportional to the area of the film, and because of a need to reduce the external resistance (R) in applications requiring a large area, a combination with a realistic R is practically impossible in some cases depending on the area. Also, a sound insulating structure is normally not comprised solely of a film but a film is used in combination with a suitable sound absorbing material. In such cases, there is a need to prepare a sound absorbing material apart from the film, causing the sound absorbing structure as the final product, to be expensive and requiring troublesome working processes for combining the sound absorbing material and the film. It is therefore difficult to realize a realistic sound insulating material with such a design.
Also, sound absorbing materials are used in various locations, such as houses, railway cars, airplanes, vehicles, etc., and the most suited material is used in accordance with the various restrictions of the location of use. In particular, the types of materials that are used in vehicles are subject to numerous restrictions in terms of weight, space, etc. and there is a need to obtain a sound absorbing structure that is more lightweight and occupying less space.
In sound absorbing structures of earlier technology structures using natural fibers, such as felt, or synthetic fibers, such as PET, are provided at locations requiring the absorption of sound and the usage amounts of such structures are increased to improve the performance. However, such a method is inefficient in that the sound absorbing performance is not improved as compared to the problems of increased cost and weight due to increased usage amount. In particular, the abovementioned method is unable to efficiently improve the sound absorbing performance at low frequencies of 500 Hz or less, and liable to become factors leading to excessive increases in cost, weight, and space.
Among acoustic noises in engine compartment, the noises in the intake system is especially problematical. To reduce the intake noises, various noise reducing systems are proposed by documents D3 (Japanese Utility Model Publication No S55-167562), D4 (Published Japanese Patent Application Kokai Publication No. S64-53055), D5 (Published Japanese Patent Application Kokai Publication No. S62-110722), D6 (Published Japanese Patent Application Kokai Publication No. S55-60444), D7 (Published Japanese Patent Application Kokai Publication No. H2-19644), D8 (Published Japanese Patent Application Kokai Publication No. H5-18329), and D9 (Published Japanese Patent Application Kokai Publication No. H5-18330).
It is therefore an objective of the present invention to provide energy conversion objects or product made from fiber which are advantageous in weight reduction and size reduction, and in sound reducing performance.
It is another objective of the present invention to provide a fiber or fibrous object or product capable of reducing sound by consuming energy of sound or vibration, and especially suitable for vehicles and other applications.
According to the present invention, a product or object, such as fiber, fiber material, a fiber body, a mass of fibers, fabric, sound reducing material, or sound reducing panel, sheet, mat, lining or laminate, comprises: at least a fiber comprising an energy consuming component to consume energy of at least one of vibration and sound by energy conversion. Preferably, the product comprises a fiber body which comprises fibers each of which comprises a thermoplastic component comprising a thermoplastic resin, and the energy consuming component. Preferably, the energy consuming component comprises a piezoelectric component having piezoelectric property; and the fiber body is a collection of fibers containing a thermoplastic resin as a Main component.